Composite containers (usually spirally wound) are used for packaging a wide variety of products including food products, such as PRINGLES.RTM. potato chips. These composite containers typically have a metal end seamed onto the container on a lower end thereof and a membrane bonded to the upper end of the composite container which usually has an outwardly turned flange on the upper end for receiving the membrane.
The bond between the membrane and the outwardly turned flanged upper end of the composite container, as well as the metal end seamed lower end of the composite container, must be hermetic and have a strength sufficient to withstand high internal pressures developed inside the container at high altitudes and/or temperature after being packaged with a food product or the like. The bond between the membrane and the flanged upper end of the composite container must also be weak enough to be opened easily without tearing the membrane during the opening. These opposed structural characteristics have presented problems in either having a membrane to container bond which is too weak to withstand the internal pressures developed at high altitudes and/or temperatures or too strong to provide easy-opening without tearing the membrane.